This is I can say....when we get exercise, our heart will beat faster because the blood needs more oxgen. so in order to make the blood get enough oxygen, Adrenaline hormone is working by enlarging the blood vine and stimulate the heart work by make it faster. As a result, our blood vines are larger and we get more sweats because more oxgen means more burning (oxydative) process.

Mithril is right. In the process of cellular respiration, only 40% of the energy is lost through ATP, the rest is turned into heat. But humans are homeoterm organisms, our body temperature is constant. So the body solves that problem by sweating... As the sweat evaporates from our skin it cools our body. That is why you need to drink a lot of water when you are exercising

"As a biologist, I firmly believe that when you're dead, you're dead. Except for what you live behind in history. That's the only afterlife" - J. Craig Venter

So that's why they're called homeothermic, I just took the sat2 and that was one of the questions....which animal is homeothermic and has placenta.....thank god the only placental mammal there was "cow"

Living one day at a time; Enjoying one moment at a time; Accepting hardships as the pathway to peace; ~Niebuhr

I mean, because of the oxydative process when we exercise is getting faster, it produces heat as the result of the process..As you said, our oxydation process isn't perfectly efficient..it produces heat as a side matter. because of this heat that makes our body feel hotter then our skin try to release it by enlarge the pore and sweating (it's kinda like reduce the heat by using water). I think that why our body temperature is constant and of course because of that we need more water to replace it.